Write generates bad paths when run from Windows

[gleeds]

When a write operation is run on a Windows machine, it copies all of the files in sub directories to the root of the S3 bucket with backslashes in their name. For example if you are writing a file that has the Windows path:

\api\index.html

You would end up with a file in the root of your s3 bucket named literally "\api\index.html" including the backslashes in the filename.